U.S. Secretary of State Condoleezza Rice called Palestinian Authority chief Mahmoud Abbas to urge a crackdown on terrorism after Monday's suicide bombing in the Israeli coastal town of Netanya. The international Middle East diplomatic "Quartet" separately called on Syria to move against the group claiming responsibility for the attack, Palestinian Islamic Jihad.

The United States is reacting with alarm to the Netanya attack, which threatens to further jeopardize Middle east peace efforts following Israel's Gaza withdrawal, including the Gaza crossing points agreement brokered by Secretary Rice last month.

The secretary of state responded to the bombing in an airborne news conference as she headed to Berlin to begin a four-nation European trip. She said the suicide attack, the first of its kind since October, requires a response by the Palestinian authority:

"Clearly, there are people who wish to arrest potential progress toward [the] peace Israel and the Palestinians are trying to make. This does call upon the Palestinians to fight terror, and to begin to deal with the terrorist organizations who are in their midst," she said. "Clearly, there are terrorist organizations who do who do not intend to be part of a national consensus, but rather intend to try to continue to kill innocent people."

Ms. Rice said she had spoken to Israeli officials to express U.S. condolences, and officials said she later spoke from the aircraft to Mr. Abbas. The secretary also said U.S. security envoy General William Ward would be talking to both parties to try and see, in her words "if we can keep matters on track."

One focus of U.S. attention is getting the sides to meet a series of deadlines for implementing the Gaza checkpoints accord, which Israeli officials allege was violated last week when exiled members of the Islamic militant group Hamas entered Gaza from Egypt.

Responsibility for Monday's Netanya bombing was claimed by Palestinian Islamic Jihad, which has remained outside the cease-fire by Palestinian factions in effect since March.

The Middle East diplomatic Quartet, which includes Russia, the European Union, the United Nations and the United States, issued a statement denouncing the attack, while urging all parties to exercise restraint, avoid an escalation of violence, and keep channels of communication open.

The Quartet also reiterated its demand that the Syrian government take immediate action to close offices of Palestinian Islamic Jihad in Syria, and prevent the use of its territory by armed groups engaged in terrorist acts.

The four parties said it is "imperative" that all involved act "decisively" to ensure that terror and violence are not allowed to undermine progress under its road map to Middle East peace.